Securities regulators in the U.S. and Canada are probing whether a recent news report about a possible purchase of BlackBerry Ltd. by Samsung Electronics Co. was sparked by investors intent on manipulating the Canadian smartphone maker’s stock.

The Securities and Exchange Commission and the Ontario Securities Commission are in the early stages of examining trading activity around the time of a report by Reuters in January that Samsung was pursuing a takeover of BlackBerry for as much as $7.5 billion, according to people familiar...